Implantable medical device detachment system with flexible braid section

ABSTRACT

The disclosed technology includes a detachment system for delivering an implantable medical device to a target location of a body vessel including a proximal delivery tube, a distal delivery tube, and a braid segment disposed between. The distal tube includes a proximal end, a distal end, and a compressible portion of the tube itself, between the proximal and distal ends which is axially movable from a compressed to an elongated condition. The proximal tube has a proximal end and a distal end. The braid segment is formed from a plurality of wires. An engagement system engages and deploys the implantable medical device engaged at the distal end of the distal tube.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 16/916,565 filed Jun. 30, 2020. The entire contentsof which are hereby incorporated by reference.

FIELD OF INVENTION

This invention generally relates to interventional medical devicesystems that are navigable through body vessels of a human subject. Moreparticularly, this invention relates to detachment systems fordelivering and deploying an implantable medical device to a targetlocation of a body vessel and methods of using the same.

BACKGROUND

The use of catheter delivery systems for positioning and deployingtherapeutic devices, such as dilation balloons, stents and emboliccoils, in the vasculature of the human body has become a standardprocedure for treating endovascular diseases. It has been found thatsuch devices are particularly useful in treating areas where traditionaloperational procedures are impossible or pose a great risk to thepatient, for example in the treatment of aneurysms in cranial bloodvessels. Due to the delicate tissue surrounding cranial blood vessels,especially for example brain tissue, it is very difficult and oftenrisky to perform surgical procedures to treat defects of the cranialblood vessels. Advancements in catheter deployment systems have providedan alternative treatment in such cases. Some of the advantages ofcatheter delivery systems are that they provide methods for treatingblood vessels by an approach that has been found to reduce the risk oftrauma to the surrounding tissue, and they also allow for treatment ofblood vessels that in the past would have been considered inoperable.

Typically, procedures using catheter deployment systems to treat ananeurysm involve inserting the distal end of a delivery catheter intothe vasculature of a patient and guiding it through the vasculature to apredetermined delivery site. A vascular occlusion device, such as anembolic coil, can be attached to an implant engagement/delivery systemat a distal end of a delivery member (e.g. microcatheter) which pushesthe coil through the delivery catheter and out of the distal end of thedelivery catheter into the delivery site. Example delivery members andengagement/delivery systems are described in U.S. Patent PublicationNumber 2019/0192162 A1, U.S. Patent Publication Number 2019/0328398 A1,and U.S. Patent Publication Number 2021/0001082 A1, each of which areincorporated herein by reference.

Many catheter-based implant delivery systems can include one or moreinner elongated member(s) extending through the catheter that can bemanipulated at the proximal end by a physician to deploy the implantabledevice. The inner elongated member can retain the implantable device inthe catheter until the time for release of the implant. These systemscan be actuated by retracting or pulling the elongated member relativeto the catheter. Some of the challenges that have been associated withproperly executing such aneurysm treatment procedures include ensuringthe delivery member and engagement system remain in a stable positionthroughout a treatment. For example, in some aneurysm treatmentapplications, as the aneurysm becomes increasingly packed with embolicmaterial, the delivery member can tend to shift due to increasingpushback from the embolic material being implanted. If the deliverymember shifts during treatment, a physician may not be able toaccurately control placement of embolic material and may choose to ceasepacking the aneurysm. In such an example, the aneurysm may not besufficiently packed, which can lead to recanalization. Further,excessive movement or stretching of the delivery member and/orengagement system thereon can result in premature detachment of theembolic coil. Some examples of ways to mitigate the likelihood ofpremature release can result in a less flexible mechanical releasesystem.

Additionally, catheter deployment systems can be used to treatintravascular lesions associated with intracranial atherosclerosisdisease (ICAD). In some instances, an intravascular lesion may not besoft enough for a stentriever to effectively engage and remove thelesion from the blood vessel. In such case, it can be desired to deploya stent such that the intravascular lesion can be treated by stenting. Aphysician may not know whether the lesion is better treated by a stentor stentriever prior to delivery of either device. Because a stentrieveris retractable and a stent typically is not, in such cases, thestentriever is typically deployed in a first pass, followed by the stent(if appropriate) in a second pass. Multiple passes through vasculaturecan increase trauma to vasculature and increase treatment time, therebyincreasing the likelihood of complications.

Thus, there is a need for systems, devices, and methods that canmitigate the likelihood of premature deployment of an intravasculartreatment device while also providing a flexible mechanical releasesystem.

SUMMARY

Generally, it is an object of the present invention to provide adetachment system for delivering an implantable medical device to atarget location of a body vessel that includes a proximal delivery tube,a distal delivery tube, and a braid segment disposed between. The braidsegment provides stability during the deployment of the implantabledevice in the aneurysm, while maximizing flexibility of the detachmentsystem.

An example detachment system for delivering an implantable medicaldevice to a target location of a blood vessel can include a generallyhollow proximal tube, a generally hollow distal tube, a braid segment,and an engagement system. The proximal tube can include a proximal endand a distal end. The distal tube can include a proximal end, a distalend, and a compressible portion of the distal tube itself which isaxially moveable from a compressed condition to an elongated condition.The braid segment can be disposed between the proximal end of the distaltube and the distal end of the proximal tube. The braid segment can beformed from a plurality of wires. The engagement system can beconfigured to engage and deploy the implantable medical device that isdisposed at the distal end of the distal tube.

The braid segment can be concentrically disposed around a polymer liner.

A polymer sleeve can be positioned over the proximal tube, the braidsegment, and at least a portion of the distal tube.

The polymer sleeve can include one or more hydrophilic coatings.

The polymer sleeve can have a wall having a thickness of betweenapproximately 0.02 millimeters and approximately 0.08 millimeters.

The braid segment can include between approximately 8 and approximately16 wire segments.

The braid segment can be constructed to have a pick per inch of betweenapproximately 50 and approximately 100.

The compressible portion of the distal tube can be a spiral-cut portionof the distal tube.

The engagement system can be configured to move the compressible portionto the compressed condition when engaging the implantable medical deviceand deploy the implantable medical device when releasing thecompressible portion to the elongated condition.

The compressible portion can be adapted to automatically move to theelongated condition when the engagement system is disengaged from theimplantable medical device.

In one example, the implantable medical device can be a stentriever whenengaged to the engagement system, the stentriever having a proximal endcollapsed by the engagement system and a distal end collapsed by theengagement system. The implantable medical device can be a stent whendisengaged from the engagement system, the stent having an open proximalend and an open distal end.

An example method of detaching an implantable medical device can includeone or more of the following steps presented in no particular order. Themethod can further include additional steps as appreciated andunderstood by a person of ordinary skill in the art according to theteachings of this disclosure.

The method can include forming a compressible portion on a distal tube;forming a flexible portion on a proximal tube; attaching a braid segmentto a distal end of a proximal tube and a proximal end of the distaltube; and engaging the implantable medical device with an engagementsystem.

The method can further include sliding a polymer sleeve over theproximal tube, the braid segment, and at least a portion of the distaltube.

The method can further include engaging the polymer sleeve to theimplantable medical device.

The method can further include coating the polymer sleeve with one ormore hydrophilic coatings.

The method can include wrapping the braid segment around a polymer linerprior to attaching the braid segment to the distal end of the proximaltube and the proximal end of the distal tube.

The engagement step can include using the loop wire with the lockingmember to engage the implantable medical device and applying force tothe loop wire to move the compressible portion to the compressedcondition.

The method can further include applying a force on the locking member,disengaging the implantable medical device, and allowing thecompressible portion to return to the elongated condition.

The method can include deploying the implantable medical device engagedby moving the compressible portion to the elongated condition.

In one example, the implantable medical device can be a stentrieverconfigured to expand to appose a wall of a blood vessel upon deployment.

BRIEF DESCRIPTION OF DRAWINGS

The above and further aspects of this invention are further discussedwith reference to the following description in conjunction with theaccompanying drawings, in which like numerals indicate like structuralelements and features in various figures. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingprinciples of the invention. The figures depict one or moreimplementations of the inventive devices, by way of example only, not byway of limitation.

FIG. 1A is an illustration of an example detachment system having abraid segment and FIG. 1B is a cross-sectional view of the exampledetachment system of FIG. 1A, according to aspects of the presentinvention;

FIG. 2A is an illustration of an additional example detachment systemhaving a braid segment, according to aspects of the present invention;

FIG. 2B is a cross-sectional view of the example detachment system ofFIG. 2A, according to aspects of the present invention;

FIG. 3A is an illustration of an additional example detachment system,according to aspects of the present invention;

FIG. 3B is a cross sectional view of the example detachment system ofFIG. 3A, according to aspects of the present invention;

FIG. 4A is a side perspective view of an example of a loop wire,according to aspects of the present invention;

FIG. 4B is a plane view of an example of a loop wire according toaspects of the present invention;

FIG. 4C is rear perspective detail view of an opening of the loop wirein an up-turned condition, according to aspects of the presentinvention;

FIGS. 5A-5D are a series of illustrations of an example implantablemedical device being detached, according to aspects of the presentinvention;

FIGS. 6A-6C are a series of illustrations of deployment of an examplestentriever as the implantable medical device, according to aspects ofthe present invention;

FIGS. 7A-7B are a series of illustrations of an example stentrieverbeing detached, according to aspects of the present invention;

FIGS. 8A-8C are illustrations of an additional example stentrieverattached to a deployment system (FIG. 8A), in cross-section (FIG. 8B),and being detached from the deployment system (FIG. 8C), according toaspects of the present invention;

FIG. 9 is a side view of an example of the distal tube in the compressedand expanded state, according to aspects of the present invention; and

FIG. 10 is a flow diagram outlining the steps of detaching animplantable medical device, according to aspects of the presentinvention.

DETAILED DESCRIPTION

A key success factor in intravascular treatment such as aneurysmtreatments is for the detachment device (e.g. microcatheter) to remainstable during the deployment of an implant or other medical treatmentdevice. During an intravascular treatment, lack of flexibility of adistal portion of a detachment device can cause the detachment device topull back from the treatment site or otherwise move out of positionwhile the implant is being placed in an aneurysm or other treatmentsite. A detachment device having a more flexible distal portion cantherefore provide a stable system for delivering medical devices inneurovascular anatomy in addition to other applications facing a similarchallenge. Flexible structures, however can tend to deform, extend, orexpand when navigating tortuous anatomy. Deformation of the detachmentsystem can inhibit the detachment system's ability to navigate to atreatment site and/or effectively deploy the medical device. Elongationof the detachment system can result in premature deployment of themedical device. An object of the present invention is to provide adetachment system having a highly flexible braided segment that isstretch resistant and structurally stable throughout delivery anddeployment of a medical treatment device.

Although example embodiments of the disclosed technology are explainedin detail herein, it is to be understood that other embodiments arecontemplated. Accordingly, it is not intended that the disclosedtechnology be limited in its scope to the details of construction andarrangement of components set forth in the following description orillustrated in the drawings. The disclosed technology is capable ofother embodiments and of being practiced or carried out in various ways.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. By “comprising”or “containing” or “including” it is meant that at least the namedcompound, element, particle, or method step is present in thecomposition or article or method, but does not exclude the presence ofother compounds, materials, particles, method steps, even if the othersuch compounds, material, particles, method steps have the same functionas what is named.

In describing example embodiments, terminology will be resorted to forthe sake of clarity. It is intended that each term contemplates itsbroadest meaning as understood by those skilled in the art and includesall technical equivalents that operate in a similar manner to accomplisha similar purpose. It is also to be understood that the mention of oneor more steps of a method does not preclude the presence of additionalmethod steps or intervening method steps between those steps expresslyidentified. Steps of a method may be performed in a different order thanthose described herein without departing from the scope of the disclosedtechnology. Similarly, it is also to be understood that the mention ofone or more components in a device or system does not preclude thepresence of additional components or intervening components betweenthose components expressly identified.

As discussed herein, vasculature can be that of any “subject” or“patient” including of any human or animal. It should be appreciatedthat an animal may be a variety of any applicable type, including, butnot limited thereto, mammal, veterinarian animal, livestock animal orpet type animal, etc. As an example, the animal may be a laboratoryanimal specifically selected to have certain characteristics similar toa human (e.g., rat, dog, pig, monkey, or the like). It should beappreciated that the subject may be any applicable human patient, forexample.

As discussed herein, the terms “about” or “approximately” for anynumerical values or ranges indicate a suitable dimensional tolerancethat allows the part or collection of components to function for itsintended purpose as described herein. More specifically, “about” or“approximately” may refer to the range of values±20% of the recitedvalue, e.g. “about 90%” may refer to the range of values from 71% to99%.

The figures illustrate a generally hollow or tubular structure accordingto the present invention. When used herein, the terms “tubular” and“tube” are to be construed broadly and are not limited to a structurethat is a right cylinder or strictly circumferential in cross-section orof a uniform cross-section throughout its length. For example, thetubular structure or system is generally illustrated as a substantiallyright cylindrical structure. However, the tubular system may have atapered or curved outer surface without departing from the scope of thepresent invention.

FIGS. 1A-3B illustrate examples of detachment system 10 wherein isdisclosed herein and addresses these and other drawbacks of previousapproaches. The detachment system 10 can include a proximal deliverytube 100 and a distal delivery tube 300. A braid segment 200 a, 200 b,200 c can be disposed between the proximal delivery tube 100 and thedistal delivery tube 300. The braid segment 200 a, 200 b, 200 c can beformed from a plurality of wires 202. The braid segment 200 b can bewrapped around a polymer liner 204 to minimize friction when deliveringthe detachment 10 and to protect the braid segment 200 b. A polymersleeve 206 can be disposed over the braid segment 200 c to furtherminimize friction and protect the braid segment 200 c. The braid segment200 a, 200 b, 200 c allows the detachment system 10 to remain stableduring deployment of the implantable medical device 12 while alsoproviding sufficient flexibility that minimizes the potential of thedetachment system 10 to move or pull back out of position while theimplantable medical device is being positioned in an aneurysm.

Examples of detachment systems 10 of the present invention, asillustrated in FIGS. 1A through 3B can have a proximal elongateddelivery tube 100, a braid segment 200 a, 200 b, 200 c, and a distaldelivery tube 300. An implantable medical device 12 can be engaged atthe distal end 304 of the distal delivery tube 300. The implantablemedical device 12 can be an embolic coil. The implantable medical device12 can be a stent retriever 612 as illustrated in FIGS. 6A, 6B, 7A, 7B,8A through 8C, alternative thereto, or variation thereof. Although theimplantable medical device 12 is illustrated as an embolic coil or astent retriever 612 herein, it will be appreciated that virtually anyimplantable medical device 12 may be delivered and deployed by thedetachment system 10 according to the present invention. The implantablemedical device 12 can be engaged to the detachment system 10 using alocking member 140 and a loop wire 400. The implantable medical device12 can have a locking portion 18 to interface with an engagement system140, 400.

The proximal delivery tube 100 can have a proximal end portion 102, adistal end portion 104, and a flexible portion 106. The flexible portion106 can be disposed between the proximal end portion 102 and the distalend portion 104. The proximal delivery tube 100 can have an axial lumentherein. The distal delivery tube 300 can have a proximal end portion302, a distal end portion 304, and a compressible portion 306. Thecompressible portion 306 can be disposed between the proximal endportion 302 and the distal end portion 304. The compressible portion 306can be closer to the distal end portion 304. The distal delivery tube300 can form an axial lumen therein.

The delivery tubes 100, 300 can be made of a biocompatible material,such as stainless steel. The delivery tubes 100, 300 can have a diameterof between about 0.25 millimeters (0.010 inch) and about 0.46millimeters (0.018 inch). In one example, the delivery tubes can have adiameter of approximately 0.37 millimeters (0.0145 inch). These examplesof tube size are suitable for delivering and deploying embolic coils totarget locations, typically aneurysms, within the neurovasculature. Itis contemplated that differently sized delivery tubes 100, 300 comprisedof other materials can be useful for different applications and arewithin the scope of the present invention.

The flexible portion 106 of the proximal delivery tube 100 can allow theproximal delivery tube 100 to bend and flex. This ability can assisttracking the detachment system 10 through the catheter and the tortuouspath through the human vasculature. The flexible portion 106 can beformed with interference spiral cuts. These cuts can allow for gaps topermit bending but in one example, do not act as a spiral-cut spring. Inthis configuration, the interference spiral cuts can bend and flex butdo not compress.

The compressible portion 306 is axially adjustable between an elongatedcondition and a compressed condition. The compressible portion 306 canbe formed from a spiral-cut portion of the distal delivery tube 300 by alaser-cutting operation. However, it is contemplated that any otherarrangement allowing axial adjustment (e.g., a wound wire or spiralribbon) is also suitable for use with detachment systems according tothe present invention. The compressible portion 306 can be in theelongated condition at rest and automatically or resiliently return tothe elongated condition from a compressed condition, unless otherwiseconstrained. The detachment device 10 can include a loop wire 400 thattogether with the locking member 140 are configured to secure theimplant 12 to the detachment device 10. The compressible portion 306 canbe maintained in a compressed condition via tension in the loop wire 400when the loop wire 400 and locking member 140 are engaged to the implant12. The loop wire 400 can be affixed to the distal delivery tube 300near the proximal end 302 of the distal delivery tube 300.

The braid segment 200 a, 200 b, 200 c can be disposed between theproximal end 302 of the distal delivery tube 300 and the distal end 104of the proximal delivery tube 100. The braid segment 200 a, 200 b, 200 ccan be affixed to the proximal end 302 of the distal delivery tube 300and the distal end 104 of the proximal delivery tube 100. The braidsegment 200 a, 200 b, 200 c can be affixed to the proximal end 302 ofthe distal delivery tube 300 and the distal end 104 of the proximaldelivery tube 100 using any attachment mechanism including but notlimited to, adhesives, welding, or the like. The proximal delivery tube100 can extend a majority of the length of the detachment system 10,while the braid segment 200 a, 200 b, 200 c and the distal delivery tube300 can extend over the most distal portion of the detachment system. Inone example, the braid segment 200 a, 200 b, 200 c and the distaldelivery tube 300 can extend over the most distal 500 millimeters of thedetachment system 10.

The braid segment 200 a, 200 b, 200 c can be formed from a plurality ofwires 202. The plurality of wires 202 can be made of a biocompatiblematerial, such as stainless steel or nitinol. The plurality of wires 202can include round wires. Alternatively or in addition to, the pluralityof wires 202 can include flat wires. The plurality of wires 202 caninclude between approximately 6 wires to approximately 20 wires. Thebraid segment 200 a, 200 b, 200 c can be constructed with various picksper inch. In one example, the braid segment 200 a, 200 b, 200 c can beconstructed with between approximately 50 picks per inch toapproximately 100 picks per inch. The number of wires in the pluralityof wires 202 and the picks per inch can result in the braid segment 200a, 200 b, 200 c having a reduced cross-section dimension prior tokinking when a hollow member is bent. By reducing a cross-sectiondimension, the braid segment 200 a, 200 b, 200 c can be substantiallyoval shaped. The number of wires in the plurality of wires 202 and thepicks per inch can facilitate elongation of the braid segment 200 a, 200b, 200 c such that the braid segment 200 a, 200 b, 200 c can resiststretching when the detachment system 10 is withdrawn in a blood vesselBV while the implant 12 is held in the aneurysm by friction.Additionally, elongation of the braid segment 200 a, 200 b, 200 c caninhibit the braid segment 200 a, 200 b, 200 c from compressing axiallyor radially collapsing when the compressible portion 106, 206, 306 is ina compressed configuration prior to deployment.

When the detachment device 10 is assembled, the braid segment 200 a, 200b, 200 c can be more flexible than the proximal delivery tube 100 andthe distal delivery tube 300. One way to measure flexibility is toperform a three-point bend test wherein a portion of a detachment system10 is held fixed at two end points, a force is applied perpendicularlyto the detachment system 10 centrally between the points, andflexibility is quantified by the length of deflection of the detachmentsystem 10 caused by the force. When measured this way, in some examples,the braid section 200 a, 200 b, 200 c can be more flexible than thedistal delivery tube 300 and more flexible than the proximal deliverytube 100. In other words, when the three-point test is performedidentically on the three sections 100, 200 a, 200 a, 200 c, 300, thebraid segment 200 a, 200 b, 200 c can deflect over a length that isgreater than the deflection length of the distal delivery tube 300 andgreater than the length of deflection of the proximal delivery tube 100.Flexibility can be measured in other ways as would be appreciated andunderstood by a person of ordinary skill in the art.

The flexible braid segment 200 a, 200 b, 200 c can be more flexible thanthe relatively stiff proximal delivery tube 100 and the relativelyflexible distal delivery tube 300. The relatively stiff proximaldelivery tube 100 extending a majority of the length of the detachmentsystem 10 can resist kinking while being pushed through a microcatheter.The flexible braid 200 a, 200 b, 200 c and the distal delivery tube 300can each be sufficiently flexible to reduce the effects of push-backwhen the implantable medical device 12 is being placed in an aneurysm.Because the flexible braid segment 200 a, 200 b, 200 c does not have tobe compressible resilient like the distal tube, the flexible braidsegment 200 a, 200 b, 200 c can have greater flexibility than the distaldelivery tube 300. By varying the pick per inch, the number of wiresegments, and/or the size of each of the wire segments in the pluralityof wires 202, compressibility and elongation of the detachment system10, including the flexible braid segment 200 a, 200 b, 200 c can beprecisely manipulated and/or controlled.

As illustrated in FIGS. 1A and 1B, the braid segment 200 a can disposedbetween the proximal delivery tube 100 and the distal delivery tube 300.The locking member 140 can be disposed within a lumen of the braidsegment 200 a. The locking member 140 can be translatable at least inthe proximal direction in relation to the distal end 304 of the distaldelivery tube 300. The plurality of wires 202 of the braid segment 200 acan be exposed. In this configuration, the braid segment 200 a is notcovered by a polymer sleeve 206 or any other protective covering. Inthis configuration, the plurality of wires 202 can be exposed to theinterior walls of blood vessels during delivery of the detachment system10 to the desired location in the patient.

FIG. 2A illustrates the detachment system 10 having a braid segment 200b concentrically disposed around a polymer liner 204. The polymer liner204 can be a polytetrafluorothylene (PTFE) liner. The polymer liner 204can provide stability to the braid segment 200 b and reduce frictionbetween the braid segment 200 b and the locking member 140 disposedwithin the lumen of the braid segment 200 b. The braid segment 200 b canbe wrapped around the polymer liner 204 prior to the braid segment 200 band polymer liner 204 being attached to the proximal delivery tube 100and the distal delivery tube 300 or the polymer liner 204 can be aseparate entity placed inside the entire length of the device includingat least a portion of the proximal delivery tube 100, at least a portionof the distal delivery tube 300, and at least a portion of the braidsegment 200 b.

FIG. 2B illustrates a cross-sectional view of the braid segment 200 bwrapped around the polymer liner 204. The polymer liner 204 can havesubstantially the same shape as the proximal delivery tube 100 and thedistal delivery tube 300. The polymer liner 204 can be substantiallytubular and can have a lumen disposed therethrough. The locking member140 can be slidably disposed within the lumen of the polymer liner 204.

FIG. 3A illustrates the detachment system 10 having a braid segment 200c surrounded by a polymer liner 204 and a polymer sleeve 206 positionedover at least a portion of the proximal delivery tube 100, the braidsegment 200 c, and at least a portion of the distal delivery tube 300.The polymer sleeve 206 can be slidably disposed over at least a portionof the proximal delivery tube 100, the braid segment 200 c, and at leasta portion of the distal delivery tube 300 after assembly of thedetachment system 10. In one example, the polymer sleeve 206 can bepositioned over at least a portion of the flexible section 106 of theproximal delivery tube 100 to inhibit deformation of the flexiblesection 106 and/or reduce friction with vasculature and the flexiblesection 106 during intravascular navigation. In one example, the polymersleeve 206 can be positioned over the entire distal delivery tube 300such that the polymer sleeve 206 can be affixed proximate to theimplantable medical device 12. In one example, the polymer sleeve 206can be glued to the distal delivery tube 300 and/or proximal deliverytube 100. Alternatively or in addition to, the polymer sleeve 206 can befused over the braid segment 200 c such that the polymer sleeve 206 canbe incorporated into the braid segment 200 c. The polymer sleeve 206 canbe affixed to the implantable medical device 12 using an attachmentmechanism including adhesives, fusion, welding, or the like. The polymersleeve 206 can be a thermoplastic elastomer sleeve. The polymer sleeve206 can include one or more additives to increase lubricity so that thesleeve can easily slide through a body vessel.

The polymer sleeve 206 can provide stability to the braid segment 200 cand reduce friction while delivering the detachment system 10 to thedesired location in a patient. The polymer sleeve 206 can protect thebraid segment 200 c as the detachment system 10 is transported throughthe vasculature and to the desired location in a patient.

FIG. 3B illustrates a cross-sectional view of the detachment system 10illustrated in FIG. 3A. The polymer sleeve 206 can have a wall 210 witha thickness between approximately 0.02 millimeters to approximately 0.08millimeters. In one example, one or more hydrophilic coatings 208 can beapplied to the polymer sleeve 206. The one or more hydrophilic coating208 can include hyaluronic acid, polyalkylene glycols, alkoxypolyalkylene glycols, poly(saccharide), poly(vinylpyrrolidone),poly(vinyl alcohol), poly(acrylic acid), poly(acrylamide),poly(maleicanhydride), copolymers thereof and mixtures thereof. The oneor more hydrophilic coating 208 can further minimize friction that canoccur when delivering the detachment system 10 through the vasculatureand to the desired location in a patient.

As illustrated in FIGS. 2A and 2B, the braid segment 200 c can include apolymer liner 204. The braid segment 200 c can be concentricallydisposed around the polymer liner 204. The polymer liner 204 can providestability to the braid segment 200 c and reduce friction between thebraid segment 200 c and the locking member 140.

As illustrated in FIG. 3B, the locking member 140 can be translatablethrough the lumens of the proximal delivery tube 100 and the braidsegment 200 c. The locking member 140 can further be translatablethrough the lumen of the distal delivery tube 300, as illustrated inFIG. 3A.

Although FIGS. 3A and 3B illustrate the detachment system 10 having abraid segment 200 c concentrically disposed around a polymer liner 204and a polymer sleeve 206 disposed over the at least a portion of theproximal delivery tube 100, the braid segment 200 c, and at least aportion of the distal delivery tube 300 after assembly of the detachmentsystem 10, it is contemplated that in some instances the braid segment200 c is not disposed around the polymer liner 204.

FIGS. 4A through 4C illustrate examples of the loop wire 400. The loopwire 400 can be relatively small, having the thickness of a hair in someexamples. Because of the small size of the loop wire 400, the loop wire400 can be entirely shielded by the distal end 304 of the distaldelivery tube 300 to prevent damage from accidental contact. The loopwire 400 can be an elongated wire that is looped to form an opening 405,as illustrated in FIG. 4A. The loop wire 400 a can also be a singleelongated wire with an opening 405 a, as illustrated in FIG. 4B. Theopening 405 can be formed by loosely bending the loop wire 400 a inhalf. In an alternative example, the loop wire 400 b can include a flatribbon defining an opening 405 b at a distal portion and the opening 405b can be in an up-turned condition suitable for engaging an end of theimplantable medical device 12 as illustrated in FIG. 4C. An example ofthe loop wire 400, 400 a, 400 b can be elastically deformable to theup-turned condition such that it will return to the substantially flatcondition when not otherwise constrained. The loop wire 400, 400 a, 400b can be formed from of any of a number of materials, including nitinoland stainless steel.

To load the detachment system 10, the locking member 140 can be insertedaxially within the lumens of the proximal delivery tube 100, the braidsegment 200 a, 200 b, 200 c, and the distal delivery tube 300. A distalend 404 of the loop wire 400 can be inserted into the distal deliverytube 300 through an anchor portion located proximate the proximal end302 of the distal delivery tube 300 as illustrated in FIG. 5A. The loopwire 400 can be passed through the lumen of the distal delivery tube 300to the distal end 304. The distal end 404 of the loop wire 400 can thenbe looped to form the opening 405. The opening 405 can be passed throughthe locking portion 18 as illustrated in FIG. 5A. The locking member 140can be passed through the opening 405 to engage the medical device 12.

FIGS. 5A through 5D, illustrate the detachment of the implantablemedical device 12 where the implantable medical device 12 is an emboliccoil. FIG. 5A illustrates the detachment system 10 with the implantablemedical device 12 engaged and the compressible portion 306 of the distalas illustrated in FIG. 5A tube 300 in the compressed state. To reach thecompressed state, the loop wire 400 can be pulled taught at a proximalend of the loop wire 400 and continued force can compress thecompressible portion 306. The amount of compression can be controlled bythe amount of force applied to the proximal end of the loop wire 400after the medical device 12 is mounted to the distal end 304 of thedistal delivery tube 300. Once the distal delivery tube 300 iscompressed the appropriate amount, the loop wire 400 can be anchorwelded at a wire weld point proximate the proximal end 302 of the distaldelivery tube 300 or proximate to the anchor portion of the distal asillustrated in FIG. 5A tube 300.

In FIG. 5A, the engagement system, including the locking member 140 andthe loop wire 400, is locked into the locking portion 18 of the medicaldevice 12. The opening 405 of the loop wire 400 can be inserted throughthe locking portion 18. When the locking member 140 is inserted throughthe opening 405 the implantable medical device 12 can be secured in thedesired position.

FIG. 5B illustrates the locking member 140 being drawn proximally tobegin the release sequence for the implantable medical device 12, asindicated by the arrow.

FIG. 5C illustrates the instant the locking member 140 exits the opening405 and is pulled free of the loop wire 400. At this instant, the distalend 404 of the loop wire 400 can return to its original, preformed shapeand can exit the locking portion 18. Once, the loop wire exits thelocking portion 18, no component is holding the implantable medicaldevice 12 to the detachment system 10.

FIG. 5D illustrates the end of the release sequence. The compressibleportion 306 can expand and return to its original, elongated condition.When the compressible portion 306 returns to its original, elongatedcondition, the compressible portion 306 can “spring” forward. An elasticforce E can be imparted by the distal end 304 of the distal deliverytube 300 to the implantable medical device 12 to “push” it away toensure a clean separation and delivery of the medical device 12 to thedesired location.

FIGS. 6A through 6C illustrate an example treatment method of a thrombusT or lesion within a blood vessel BV using the same detachment device 10as illustrated in FIGS. 1A through 3B and a stentriever 612 as themedical implant 12. The stentriever 612 can have a proximal end 614 anda distal end 616 that can include loops 618. The proximal end 614 of thestentriever 612 can be affixed to the detachment device 10. The lockingmember 140 can extend through the distal end 616 of the stentriever 612,as illustrated in FIG. 6A. The detachment device 10 and the stentriever612 can be disposed within a microcatheter 610 during delivery throughthe vasculature. The microcatheter 610 can prevent the strut framework620 of the stentriever 612 from self-expanding. In some instances, themicrocatheter 610 can cross a thrombus T or lesion within a blood vesselBV. The microcatheter 610 can be sized to maintain the stentriever 612collapsed thereon as the microcatheter 610 and stentriever 612 arepositioned across the thrombus T. The stentriever can be maintained inposition as the microcatheter 610 is retracted proximally to allow thestentriever 612 to expand to appose the walls of the blood vessel BV.

FIGS. 6B and 6C illustrate the microcatheter 610 can be drawn proximallyto allow the strut framework 620 of the stentriever 612 to begin toexpand. The strut framework 620 can self-expand to appose the walls ofthe blood vessel BV. The stentriever 612 can include loops 618 disposedat the distal end 616 and the proximal end 614. The locking member 140extending through the distal end 616 of the stentriever 612 can engagewith the loops 618, such that the distal end 616 and the proximal end614 of the stentriever 612 remain closed. By maintaining the distal end616 and the proximal end 614 in a closed configuration via the loops 618engaging with the locking member 140, when the stentriever 612 expands,it can form a substantially conical or tubular shape. Upon expanding,the strut framework 620 can engage and expand through soft material ofthe thrombus T. The detachment device 10 affixed to the proximal end 614of the stentriever 612 can then be used to facilitate removal of thestentriever 612 including the captured thrombus T from the blood vesselBV. The detachment device 10 and the stentriever 612 with the capturedthrombus T can be retracted proximally, such that the thrombus T can beeffectively removed from the blood vessel BV.

Upon crossing the affected area including the thrombus T and/or lesion,in some treatments, the thrombus material may be sufficiently soft topass through the strut framework 620 of the stentriever as illustratedin FIGS. 6B and 6C. In such cases, the stentriever 612 can remainattached to the detachment device 10 as the captured thrombus T,stentriever 612, and detachment device 10 are pulled proximally frompatient. The removal of the stentriever 612 and thrombus T from thepatient can be performed with adjunctive aspiration through a largerdiameter intermediate catheter positioned over the microcatheter withits tip in close proximity to the proximal end 614 of the stentriever612. Alternatively, the thrombus material may not be sufficiently softto pass through the strut framework 620, or there may be an underlyingnarrowing (stenosis) of the blood vessel BV after removal of thethrombus T that continues to restrict flow beyond the lesion, in whichcase the affected area may be better treated by stenting.

FIGS. 7A and 7B illustrate an additional treatment method using thedetachment device 10 and the stentriever 612 that can be applied whenstenting is appropriate. As illustrated in FIG. 7A, when themicrocatheter 610 is drawn proximally, the stentriever 612 can begin toexpand. As the stentriever 612 expands, the stentriever 612 can pressagainst the thrombus T, causing the thrombus T to press against thewalls of the blood vessel BV. The distal end 616 and/or the proximal end614 of the stentriever can include loops 618 sized to allow the lockingmember 140 to pass through. The loops 618 can be placed at intervalscircumferentially around the stentriever 612 so that when the lockingmember 140 is extended through the loops, the distal end 616 and/or theproximal end 614 has a conical shape, extending inward toward thelocking member 140 as illustrated. As the locking member 140 is drawnproximally, the closed distal end 616 of the stentriever 612 can bereleased, as the loops 618 disengaged with the locking member 140. Oncereleased, the distal end 616 can open such that the distal end 616 canappose the walls of the blood vessel BV. As the locking member 140 isfurther drawn proximally, the closed proximal end 614 of the stentriever612 can also be released. The proximal end 614 can then open such thatthe proximal end 614 can appose the walls of the blood vessel BV. Inthis configuration, the stentriever 612 is converted into a permanentlyimplantable stent which can continue to press the thrombus T against theblood vessel BV, as well as apply a chronic force against the wall ofthe blood vessel BV to open any underlying stenosis with or without theaid of a subsequently applied angioplasty balloon dilation.

As illustrated in FIG. 7B, the stentriever 612 can be detached from thedetachment device 10. Once detached, the “stentriever” 612 is no longerretrievable from the body and thereby is, effectively, a stent. Themethod of detachment of the stentriever 612 can be the same detachmentmethod as illustrated in FIGS. 5A through 5D. Once deployed, thestentriever (stent) 612 can remain across the blood vessel BV.

FIGS. 8A through 8C illustrate deployment and optional detachment of anadditional example stentriever 612 using a similar detachment method anddetachment device 10 as illustrated in FIGS. 5A through 5D. Thestentriever 612 can have a proximal end 614 and a distal end 616. Theproximal end 614 can be affixed to the detachment device 10, and moreparticularly to the distal end 304 of the distal delivery tube 300. Whenthe stentriever 612 is affixed to the detachment device 10 prior todeployment, the compressible portion 306 of the distal delivery tube 300can be in the compressed state.

As illustrated in FIG. 8A, the engagement system 140, 400 can be engagedwith the stentriever 612. The locking member 140 can extend to a distalend 616 of the stentriever 612 such that the locking member 140 extendsthrough the opening 405 of the loop wire 400. The stentriever 612 caninclude loops 618 similar to as illustrated and described in FIGS. 7Aand 7B. The stentriever 612 can, but need not, include a locking portion18 having a geometry as illustrated in FIGS. 5A and 5B. As illustratedin FIG. 8A, the loop wire 400 can be fed through the stentriever 612near the proximal end of the stentriever 612 so that the engagementbetween the loop wire 400, locking member 140, distal delivery tube 300,and stentriever 612 are configured to secure the stentriever to thedetachment device 10. The stentriever 612 can further include eyelets622 configured to maintain compression of the body of the stentriever612 during delivery. The eyelets 622 can be shaped similar to the loops618. The eyelets 622 and loops 618 can include openings sized to allowthe locking member 140 to pass therethrough. The one or more eyelets 622can be affixed to the expandable framework 620 and positioned at leastpartially around the locking member 140 such that the expandableframework 620 is prevented from pre-maturely deploying and thestentriever 612 is securely engaged with the engagement system 140, 400.In this configuration, the expandable framework 620 can be preventedfrom expanding even without the use of a catheter. In one example, theone or more eyelets 622 can be disposed along the entire stentriever612. Alternatively, the one or more eyelets can be disposed along aportion of the stentriever 612. By way of example, the one or moreeyelets 622 can be disposed along a distal portion of the stentriever612. FIG. 8B illustrates a cross-sectional view of the examplestentriever 612 as illustrated in FIG. 8A. The stentriever 612 can beaffixed to the distal delivery tube 300, such that the stentriever 612is engaged with the detachment system 10. The locking member 140 can betranslatable through the distal delivery tube 300 and can extend throughthe stentriever 612. The expandable framework 620 of the stentriever 612can include one or more eyelets 622. As illustrated in FIG. 8B, theeyelets 622 can be affixed at least partially around the locking member140 and to the expandable framework 620 such that the stentriever 612 isprevented from expanding pre-maturely.

FIG. 8C illustrates the locking member 140 can be drawn proximally tobegin the release sequence for the stentriever 612, as indicated by thearrow. When the locking member 140 is proximally drawn, the loops 618 atthe distal end 616 are released, then the eyelets 622 are released. Asthe loops 618 and eyelets 622 are released, the expandable framework 620of the stentriever 612 can begin to expand. By way of example, as thelocking member 140 is proximally drawn, the eyelets 622 disposedproximate the open distal end 616 of the stentriever 612 can be firstreleased, such that the open distal end 616 stentriever 612 can begin toexpand. As the locking member 140 is further proximally drawn, theeyelets 622 disposed proximate the proximal end 614 of the stentriever612 can be released, such that the open proximal end 614 of thestentriever 612 can expand.

At the instant the locking member 140 exits the opening 405 and ispulled free of the loop wire, the distal end 404 of the loop wire 400can return to its original, preformed shape. At this point in therelease sequence, no component is holding the stentriever 612 to thedetachment system 10, as all the eyelets 622 affixed to the expandableframework 620 are released.

After release of the stentriever 612, the compressible portion 306 canexpand and return to its original, elongated condition as illustrated inFIG. 9 . When the compressible portion 306 returns to its original,elongated condition, the compressible portion 306 can “spring” forward.An elastic force can be imparted by the distal end 304 of the distaldelivery tube 300 to the stentriever 612 to “push” it away to ensure aclean separation and delivery of the stentriever 612 to the desiredlocation. Upon detachment, the stentriever 612 can fully expand suchthat the stentriever 612 can appose the walls of the blood vessel.

FIG. 9 illustrates the distal delivery tube 300 without the implantablemedical device 12 in a compressible condition and an elongatedcondition. The compressible portion 306 can be shortened in axial lengthto the compressed condition. The compressible portion 306 can be shortedin axial length a distance D when moving from the elongated condition tothe compressed condition. This compression can occur along the axis A.

FIG. 10 is a flow diagram illustrating a method 1000 of detaching animplantable medical device. The implantable medical device can include adevice 12, 612 such as illustrated and described herein, a variationthereon, or alternative thereto as understood by a person skilled in theart according to the teachings herein. The method can include one ormore of the following steps presented in no particular order. Theexample method 1000 can include additional steps as appreciated andunderstood by a person of ordinary skill in the art. The example methodcan be performed by an example detachment system 10 as disclosed herein,a variation thereof, or an alternative thereto as appreciated andunderstood by a person of ordinary skill in the art.

In step 1005, a compressible portion 306 on a distal delivery tube 300can be formed. The compressible portion 306 on a distal delivery tube300 can be formed by spiral-cutting a portion of the distal deliverytube 300.

In step 1010, a flexible portion 106 on a proximal delivery tube 100 canbe formed. The flexible portion 106 on the proximal delivery tube 100can be formed by interreference cuts along at least a portion of theproximal delivery tube 100.

In step 1015 a braid segment 200 a, 200 b, 200 c can be attached to adistal end 104 of the proximal delivery tube 100 and a proximal end 302of the distal delivery tube 300.

In step 1020, the implantable medical device 12 can be engaged with anengagement system 140, 400. The engagement system 140, 400 can include alocking member 140 and a loop wire 400.

The method can include using the loop wire 400 with the locking member140 to engage the implantable medical device 12 and applying force tothe loop wire 400 to move the compressible portion 306 to the compressedcondition.

The method can include wrapping the braid segment 200 b around a polymerliner 204 prior to attaching the braid segment 200 b to the distal end104 of the proximal delivery tube 100 and the proximal end of the distaldelivery tube 300.

The method can include sliding a polymer sleeve 206 over the proximaldelivery tube 100, the braid segment 200 c and at least a portion of thedistal delivery tube 300. The polymer sleeve 206 can be engaged to theimplantable medical device.

The method can include engaging the polymer sleeve 206 to theimplantable medical device 12.

The method can include coating the polymer sleeve 206 with one or morehydrophilic coating 208.

During detachment, the method can include applying a force on thelocking member 140; disengaging the implantable medical device 12; andallowing the compressible portion 306 to return to the elongatedcondition. By moving the compressible portion 306 to the elongatedcondition, the implantable medical device 12 can be deployed.

The descriptions contained herein are examples of embodiments of theinvention and are not intended in any way to limit the scope of theinvention. As described herein, the invention contemplates manyvariations and modifications of the inventive delivery and releasesystem for a vascular occlusion device, including numerousconfigurations, numerous stiffness properties and methods for deliveringthe same. Also, there are many possible variations in the materials andconfigurations of the release mechanism. These modifications would beapparent to those having ordinary skill in the art to which thisinvention relates and are intended to be within the scope of the claimswhich follow.

1. A detachment system for delivering an implantable medical device to atarget location of a body vessel (BV), comprising: a generally hollow,relatively stiff proximal tube having a proximal end and a distal end,the distal end comprising a flexible section; a generally hollow,relatively flexible distal tube comprising: a proximal end; a distalend; and a compressible portion of the relatively flexible distal tubeitself which is axially movable from a compressed condition to anelongated condition; a flexible braid segment disposed between theproximal end of the relatively flexible distal tube and the flexiblesection of the distal end of the relatively stiff proximal tube, theflexible braid segment formed from a plurality of wires; and anengagement system configured to engage and deploy the implantablemedical device disposed at the distal end of the distal tube, whereinthe flexible braid segment is more flexible than each of the relativelyflexible distal tube and the relatively stiff proximal tube.
 2. Thedetachment system of claim 1, wherein the flexible braid segment isconcentrically disposed around a polymer liner.
 3. The detachment systemof claim 1, wherein a polymer sleeve is positioned over at least aportion of the proximal tube, the braid segment, and at least a portionof the distal tube.
 4. The detachment system of claim 1, wherein thepolymer sleeve includes one or more hydrophilic coatings.
 5. Thedetachment system of claim 1, wherein the polymer sleeve has a wallhaving a thickness of between approximately 0.02 millimeters andapproximately 0.08 millimeters.
 6. The detachment system of claim 1,wherein the flexible braid segment includes between approximately 8 andapproximately 16 wires.
 7. The detachment system of claim 1, wherein theplurality of wires have a pick per inch of between approximately 50 andapproximately
 100. 8. The detachment system of claim 1, wherein thecompressible portion of the relatively flexible distal tube is aspiral-cut portion of the relatively flexible distal tube.
 9. Thedetachment system of claim 1, wherein the flexible section of the distalend of the relatively stiff proximal tube comprises a spiral-cutportion.
 10. The detachment system of claim 1, wherein the engagementsystem is configured to: move the compressible portion to the compressedcondition when engaging the implantable medical device; and deploy theimplantable medical device when releasing the compressible portion tothe elongated condition.
 11. The detachment system of claim 1, whereinthe compressible portion is adapted to automatically move to theelongated condition when the engagement system is disengaged from theimplantable medical device.
 12. A method of detaching an implantablemedical device, comprising forming a compressible portion on a proximalend of a relatively flexible distal tube; forming a flexible portion ona distal end of a relatively stiff proximal tube; attaching a flexiblebraid assembly to the distal end of the relatively stiff proximal tubeand the proximal end of the relatively flexible distal tube; sliding apolymer sleeve over at least a portion of the flexible section of therelatively stiff proximal tube, the entirety of the flexible braidassembly, and the entirety of the relatively flexible distal tube; andengaging the implantable medical device with an engagement system,wherein the flexible braid segment is more flexible than each of therelatively flexible distal tube and the relatively stiff proximal tube.13. The detachment method of claim 12, wherein a polymer sleeve ispositioned over at least a portion of the proximal tube, the braidsegment, and at least a portion of the distal tube.
 14. The detachmentmethod of claim 13, further comprising engaging the polymer sleeve tothe implantable medical device.
 15. The detachment method of claim 13,further comprising coating the polymer sleeve with one or morehydrophilic coatings.
 16. The detachment method of claim 12, furthercomprising wrapping the flexible braid assembly around a polymer linerprior to attaching the flexible braid assembly to the distal end of therelatively stiff proximal tube and the proximal end of the relativelyflexible distal tube.
 17. The detachment method of claim 12, wherein theengagement system comprises a locking member, and a loop wire, whereinengaging the implantable medical device with the engagement systemfurther comprises using the loop wire with the locking member to engagethe implantable medical device; and wherein the applying step furthercomprises applying force to the loop wire to move the compressibleportion to a compressed condition.
 18. The detachment method of claim17, further comprising: applying a force on the locking member;disengaging the implantable medical device; and allowing thecompressible portion to return to an elongated condition.
 19. Thedetachment method of claim 12, wherein forming the compressible portionon the relatively flexible distal tube includes spiral-cutting a portionof the relatively flexible distal tube.
 20. The detachment method ofclaim 12, further comprising deploying the implantable medical device bymoving the compressible portion to an elongated condition.